1. Field of the Invention
The present invention relates to the field of particle control, particle application and to processes where particles can be supported during application and released from support.
2. Background of the Art
The application of particles to surfaces has been performed in many different ways in many different disciplines. Early paint is in fact often comprised the manufacture of a slurry of particles in a volatile (water) liquid carrier, the application of the slurry to a surface and the subsequent drying of the slurry s applied. Coloration of tiles often included glazes of particles that were applied and fired to surfaces.
Many modern technologies find the application of particles to be essential to manufacturing and performance systems. A whole new field of technology has developed revolving around the field of ultrasmall particles, nanoparticles.
Silk screen printing is one of the oldest graphic arts technologies (besides manual deposition of pigments or dyes to a surface) still in commercial use. The process was believed to have been originated by the ancient Chinese, using silk screens to deposit colorant fluids (e.g., inks) through the screen onto a surface. The technology is still used commercially today, not only for imaging, but also for manufacture of detailed patterns for circuitry, conductors, adhesives and the like. Window defrosters and antennae on car windows are sometimes still made by the process.
Few dry powder screening processes have been known to provide sufficient benefits to succeed commercially. It is believed that early Chinese artists may have manually brushed dry powder through the silk screens onto various surfaces to which the powders would adhere.
U.S. Pat. No. 4,698,907 teaches processes for the application of patterns of dry metallic powders. The processes use electrophotography, electrically charged drums, latent charge images (e.g., electrography), or dielectric webs, with metal powders applied as toners from brushes or cascade development applicator systems. It is disclosed that the metal powder is to be coated with a thin dielectric layer so that it may be electrically charged and transferred.
U.S. Pat. No. 3,166,432 teaches that electrically conducting toner particles may be applied by induction development. Indeed, many commercial copying or imaging systems use dry toner powders (usually defined as having less than 10% by weight volatile materials in fresh materials) as the toning agents. These toners often comprise a blend or other physical association of colorant (e.g., pigment or dye), binder, and charge control agent. These particles tend to be very thin layers of particles (even monolayers in may cases) when they are applied, described in Schein, Electrophotography and Development Physics, Springer Vertag, Berlin 1988, P. 180. The application of multiple layers or thick layers of toner materials may require the use of special receptor surfaces with coatings that are receptive to larger volumes of materials (e.g., U.S. Pat. No. 4,337,303, Sahyun et al.).
U.S. Pat. No. 3,081,698 described an electrostatic stencil screen printing process. Contact free printing was performed on delicate or rough surfaces by moving a dry resinous material through the openings of a stencil mask by electrostatic forces. In all cases, the toner used was a dry resinous material that could be triboelectrically charged, and a powder cloud of the material was mechanically created. In FIG. 5, the particles are apparently being suspended by air movement. The charged toner particles were projected through the mask or stencil at a relatively distant target/receptor (e.g., paper being separated from the stencil by an air gap).
U.S. Pat. No. 5,817,374 (Detig) describes that particles are applied to the surfaces of materials, especially in the form of discontinuous or patterned coatings on the surfaces of sheet materials by a process comprising the steps of: a) providing a support, b) placing a bed of non-adhered particles on the support, the particles being capable of being moved by an electric field of less than 100 KV/cm, c) placing a mask with a first and second surface over the bed of non-adhered particles, the mask having holes which pass from the first to the second surface, the first surface facing the bed of non-adhered particles without the mask touching the bed of non-adhered particles, the holes in the mask having a size which would allow passage of individual particles from the bed of non-adhered particles through the holes, d) placing a receptor material capable of at least temporarily retaining an electric charge adjacent to the second surface of the mask, which second surface faces away from the bed of non-adhered particles, e) applying an electrical charge to the receptor material which is at least temporarily retained by the receptor material, f) applying an electrical field between the mask and the support, the electrical field being of at least sufficient strength to cause individual particles from the bed of non-adhered particles to move off the first substrate and impact the mask, g) allowing some of the individual particles which move off of the support to enter the holes in the mask and contact the receptor material, and h) the contract by individual particles to the receptor material causing at least some of the particles contacting the receptor material to adhere to the receptor material at least by charge attraction of the individual particles to charge on the receptor material.
U.S. patent application Ser. No. 10/164,365, filed May 31, 2002 describes A delivery system is described for the delivery of flowable medicinal, therapeutic or medicine materials. The delivery system comprises a strip having flowable material contained and restrained therein. A removable seal is provided, so that when the removable seal is removed, the flowable material will flow from a storage area onto the site selected for treatment. The removable seal may be provided with additional features such as absorbent coatings, or additional disinfectants coatings useful in preparing the wound surface to receive the flowable wound treatment material. The delivery system may be contained in an adhesively securable element such as a bandage, band-aid, applique', wrap, patch, or the like. The system may be secured to a patient along a limited amount of the edge of the system, the removable seal removed, causing the contained material to flow, and additional edges of the system secured to the patient. The securing of the system may be effected by adhesives, such as activatable adhesives (e.g., solvent or water activated adhesive) or pressure-sensitive adhesive. A preferred composition is a system, article and method for the enhancement of clotting in wounds with extravascular blood flow, especially where the surface of the tissue has been broken. The composition consists of biotolerable, porous particulates (with pores chosen of the appropriate size for the effect desired) applied to the surface of a wound with liquid blood thereon. The porous nature of the particulate material, either free-flowing or packaged or restrained on or in a surface, enhances clotting. Chemical or biochemical agents, such as additional clotting agents, therapeutic agents, antibiotics, clot strengthening agents (such as fibrous structural materials), and the like may optionally be included on, with or within the porous particles. Where the porous particle clotting agents are used with animals, materials which are mildly repellant to the animal patient (without being toxic) may be included within the applied particle material to assure that the animal will not tamper with the wound during healing, a common problem with veterinary treatments. The particles may comprise such diverse materials as organics, metallics, inorganics, ceramics, and the like, both natural and artificial. It is generally preferred that the pore size distribution lies within a general range, and this range may vary from animal to animal and condition to condition, but generally falls within about 0.5-1000 NM or 1 to 1000 nm, or about 5 to 500 nm, depending upon the particular use. Preferred particles are those applied for the purposes of U.S. Pat. No. 6,060,461.
Additional and controllable methods for the carrying of particles and the application of particles to other surfaces are desired, including the application of particles to patients during medical procedures.